French sports and education groups expressed outrage Tuesday at the closure of around 30 swimming pools, after their operator said surging heating costs made them no longer viable.

"These closures directly impact all children and adults who won't be able to learn to swim," the French Swimming Federation (FFN) said in a statement, demanding the pools' "immediate" reopening.

Vert Marine, which operates pools and ice rinks across France, said Monday that its annual energy bill had jumped to 100 million euros ($99 million) from 15 million euros -- a figure it said equalled "the company's entire annual revenue".

The company said it was up to "local authorities and the government to take necessary and unprecedented decisions to get back to bearable energy costs".

But local governments are themselves struggling to meet surging bills, which have doubled in some places, according to France Urbaine, a federation of large towns and cities.

Physical education union SNEP warned that pool closures during the coronavirus crisis meant there was already "a generation of 800,000 school pupils who were unable to learn to swim in 2020 and 2021".

The sports ministry has also heavily promoted swimming as a way of preventing accidental drownings.

"Balancing the books for private companies that manage some pools shouldn't come before the public interest," the SNEP said, highlighting swimming's "educational, health, leisure and safety benefits".

Many of France's pools and ice rinks are old and energy-intensive, and they are set to be studied in more detail by a government working group on saving energy.